Stats Trek II: Lies, Damned Lies, and Statistics

Figures often beguile me, particularly when I have the arranging of them myself; in which case the remark attributed to Disraeli would often apply with justice and force: “There are three kinds of lies: lies, damned lies and statistics.” – Mark Twain’s Own Autobiography: The Chapters from the North American Review

The next few articles in this space will deal with the dissection of scientific papers, and how YOU, dear reader, can make the most of them, no matter if you’re starting your animal behavior journey or are interested in pursuing advanced academic training. Even as a ridiculously pedigreed college professor, I revisit these principles frequently in my responsibilities as a journal reviewer, to fight my own confirmation bias (I want chocolate to cure everything!), and to broaden my knowledge base in the areas I’m interested in.

In my Advanced Physiology class, one of my favorite assignments of the semester is to challenge my students to find a health claim on a blog, in a Facebook ad, or in a magazine article and explain that health claim via what they’ve learned about human physiology. I’ve had students investigate hormone replacement therapy, human growth hormone for weight loss; yoga; meditation, and ADHD medication side effects amongst others. We refer to these assignments as “going down the rabbit hole” because to answer our original question, we have to dive into our own assumptions and look at the evidence based on what else we know.

Our hole for this series is an article by Sankey et al entitled: “The Way to a Man’s Heart Is Through His Stomach: What About Horses?” This is a paper from PLoS One, a peer-reviewed open access journal, meaning that the data are available for public consumption, without fees. Pull it up on your web browser or download it from here.

Now, let’s stand on the edge of the hole. Glance at the abstract of the paper (don’t read it yet!). An abstract is a shortened form of the paper; typically it places the problem in context, briefly describes methods and results, and sometimes adds a little bit of spin at the end about why the paper is important. The abstract for our paper is short and sweet, read it and answer the following questions:

What is being studied?

Why is it being studied?

How is it being studied?

Now, this is where your expertise comes in. Before proceeding with the paper, take a few moments to self-evaluate: What do you know about horses? What do you know about the human-animal bond? What do you know about the human-animal bond in horses? What do you know about the bond between horses? How do you know these things? The paper proposes determining whether food or physical contact is better for strengthening the human-horse bond. What do you know about food/grooming in horses? How might you test which reinforcement promotes the bond?

Here is a secret: It doesn’t matter what your answers are. The reason we formulate the questions before we read the paper is so we can acknowledge what we do not know. This isn’t a contest, and the answers of someone with no formal scientific education are no less valid than the answers of someone in a competing research group, or a dog trainer with a solid grounding in canine behavior literature and a PhD in experimental pathology. The canonical saying is that the more expert you become in one subject, the more you realize you don’t know much about anything!

The answers to these questions about what you know tell you where your understanding places you in the intellectual landscape of the paper, and the purpose of the introduction is to pinpoint where the authors are. The best introductions put the problem being solved in context, while providing a good list of citations for you to follow their logic. For example, a paper from authors who study oxytocin release in many different species is going to read very differently than a paper from authors who study many different types of bonding in dogs and decide to test oxytocin. While reading an introduction, chronicle the author’s answers to our questions above. What do the authors know about the human-animal bond? The answer is in paragraph one. And now we’re in the rabbit hole. Read down the page, and click on the citation that follows a statement that is interesting to you. I’ve chosen [2], which takes me to:

Clicking on the View Article link will take me to the publisher’s page, where you will often find the abstract and the paper in PDF format if it is freely available. This is a review article, which means it is a curated summary of the current research at the time of publication. Review articles map out the current landscape, and suggest future directions for the field of study. Review articles, while not primary research, are excellent sources of more papers to read! One good review article on a fascinating topic can keep you in scientific reading for months. Clicking the PubMed link takes us to the NIH/National Library of Medicine repository, and this particular paper isn’t listed there. Finally, if we click Google Scholar, we not only find a free version of the paper via ResearchGate (a social media site for scientists), but we can see that this review has been cited 214 times, and get a list of the papers where it has been cited (more reading!).

The introduction goes on to further narrow down to the meat of the paper, addressing the use of food to promote the conspecific as well as inter-species bonds. The authors note that “precocial animals have a less positive perception of human contact [14].” Why did the authors note this? A quick look at citation 14 tells us that early interaction between a human and a foal may hinder the human-horse bond later in life. This is one of our clues why the authors chose the experimental subjects they did.

You may have heard of the “replication crisis” in science, where drug companies cannot replicate the work of basic scientists, and psychologists cannot replicate decades of work done by their peers. Small sample sizes and p-hacking (which we will discuss in a later article) contribute to studies being hard to replicate, but importantly, small differences in methodology or how the animals are kept can contribute to whether or not scientists get measurable results. Not only do scientists order genetically identical mice, but they do experiments at the same time every day, and even order mice from the same room at the breeding facility to ensure consistency. For results to be comparable between papers, all of the tests must have been performed under the same conditions, and so how the subjects are reared, fed, and kept is detailed in the paper. There is an excellent article about this phenomenon in mouse studies, in which different gut bacteria play a crucial role in replicability here.

The selection of experimental subjects is one of the most fraught decisions a scientist makes over the course of an experiment. I will never forget taking Tesla, my training-savvy Great Pyrenees, to Harvard for their canine cognition battery of tests. When the grad students running a pointing experiment wouldn’t interact with her after she repeatedly got the treat out of the bowl, Tess turned her back, laid down, and refused to participate. My praise wasn’t good enough, the treat wasn’t good enough, and being ignored by the grad student clearly caused her to stop playing the game. I am not sure what their hypothesis was, but I know I formulated at least 10 in the few hours we were there about training history, the human-animal bond, and reinforcement hierarchies for Tess.

Our paper lays out the breed of horse, their rearing, and, importantly, their social exposure to other horses as well as to humans before the start of the experiment. The animals were the same age, but were raised in a multi-age environment where they experienced pro-social behavior with the other horses. By clearly setting out the conditions, the authors are making a statement about the presence of potentially confounding factors. For example, all of the horses had food constantly available (ad libitum) so all of the horses would be equally receptive to carrots as reinforcement. The cohort also consisted of both stable-born and forest-born horses, and to mitigate this potential difference, these horses were randomized into social groups and raised identically after 10 months of age.

What do you do when you don’t have enough background in the type of study you are trying to read? Trust in Peer Review, and More Research! Peer review is the process by which a scientific paper is vetted by other scientists prior to publication. Ideally, a paper on the human-animal bond in horses would be read by another expert in this topic, but sometimes editors have to move farther afield to find a qualified reviewer. Despite the challenges of the peer-reviewing process, it is still the standard way journals ensure that methodology is sound and that the conclusions drawn in a paper are supported by the data. In response to the desire of the scientific community to have a platform to discuss the methodology in an individual paper, many journals are opening public comments sections (available to the left of our article in PLoS), and tracking articles in tweets, Facebook shares and posts, and website hits (available in the upper right corner of our journal article website). Independent websites have popped up such as PubPeer, where authors can be contacted and asked questions, and papers can be discussed in a public forum. A search of our paper on these websites shows that it has not been discussed on PubPeer, but this site shows what public discussion of methodology can look like.

Now that we’ve talked about how to analyze what we do and do not know about our paper, and some ways to review the methodology, it’s time to dig into the experimental setup and the data! Stay tuned for our next installment: Controls, and Graphs, and What Is Normal, Anyway?

Reference:

[1] Sankey C, Henry S, Górecka-Bruzda A, Richard-Yris M-A, Hausberger M (2010) The Way to a Man’s Heart Is through His Stomach: What about Horses? PLoS ONE 5(11): e15446. doi:10.1371/journal.pone.0015446

Jessica L. Fry PhD, KPA-CTP, is an assistant professor of biology at Curry College in Milton, Mass. She is the current president of the New England Dog Training Club, and is owned by Helix the Calico and Tesla the Pyr.